Ultrasonic imaging has become a widely used tool in medical applications. Ultrasound techniques introduce high-frequency acoustic waves into a subject's body. The received echoes of those waves provide information allowing a trained observer to view the subject's internal organs.
Ultrasound medical diagnostic equipment can operate in a variety of modes. Continuous wave (“CW”) is one such operational mode. In the CW operating mode, ultrasound energy is continuously generated and applied to a subject. An intra-body flow (e.g., flow within a blood vessel) introduces a Doppler shift in the reflected ultrasound energy. By detecting the Doppler shift in the received signal frequency, the velocity of the flow can be determined and the subject's cardiac health ascertained.
Another popular ultrasound operating mode is commonly referred to as “B-mode.” The term “B-mode” derives from the assignment of display brightness value to each ultrasonic signal reflection in accordance with the amplitude of the reflection. B-mode employs a high-amplitude, short duration pulsed ultrasound signal to produce a two-dimensional image of the subject's internal organs. The B-mode signal enters the body of the subject, is reflected off the various internal organs, and finally, is detected by a receiver. The received signal is collected and processed to form the image.
Users of ultrasound imaging systems demand both power efficiency and reduced device size in modern ultrasound equipment. Thus, it is desirable to accommodate both B-mode and CW-mode operation in an ultrasound imager that reduces component count and power dissipation.